Open Stack

> -----Original Message-----
> From: Jay Pipes [mailto:jaypipes at gmail.com]
> Sent: Monday, May 05, 2014 6:19 PM
> To: openstack-dev at lists.openstack.org
> Subject: Re: [openstack-dev] [nova] Question about addit log in
> nova-compute.log
> 
> On 05/05/2014 04:19 PM, Jiang, Yunhong wrote:
> >> -----Original Message-----
> >> From: Jay Pipes [mailto:jaypipes at gmail.com]
> >> Sent: Monday, May 05, 2014 9:50 AM
> >> To: openstack-dev at lists.openstack.org
> >> Subject: Re: [openstack-dev] [nova] Question about addit log in
> >> nova-compute.log
> >>
> >> On 05/04/2014 11:09 PM, Chen CH Ji wrote:
> >>> Hi
> >>>                  I saw in my compute.log has following logs which
> looks
> >>> to me strange at first, Free resource is negative make me confused
> and I
> >>> take a look at the existing code
> >>>                  looks to me the logic is correct and calculation
> doesn't
> >>> have problem ,but the output 'Free' is confusing
> >>>
> >>>                  Is this on purpose or might need to be enhanced?
> >>>
> >>> 2014-05-05 10:51:33.732 4992 AUDIT
> nova.compute.resource_tracker
> >> [-]
> >>> Free ram (MB): -1559
> >>> 2014-05-05 10:51:33.732 4992 AUDIT
> nova.compute.resource_tracker
> >> [-]
> >>> Free disk (GB): 29
> >>> 2014-05-05 10:51:33.732 4992 AUDIT
> nova.compute.resource_tracker
> >> [-]
> >>> Free VCPUS: -3
> >>
> >> Hi Kevin,
> >>
> >> I think changing "free" to "available" might make things a little more
> >> clear. In the above case, it may be that your compute worker has both
> >> CPU and RAM overcommit enabled.
> >>
> >> Best,
> >> -jay
> >
> > HI, Jay,
> > 	I don't think change 'free' to 'available' will make it clearer.
> > 	IMHO, the calculation of the 'free' is bogus. When report the status in
> the periodic task, the resource tracker has no idea of the over-commit
> ration at all, thus it simply subtract the total RAM number assigned to
> instances from the RAM number provided by hypervisor w/o considering
> the over-commitment at all. So this number really have meaningless.
> 
> Agreed that in it's current state, it's meaningless. But... that said,
> the numbers *could* be used to show oversubscription percentage, and
> you
> don't need to know the max overcommit ratio in order to calculate that
> with the numbers already known.

I don't think user can use these number to calculate the 'available'. User has to know the max overcommit ratio to know the 'available'. Also, it's really ironic to provide some meaningless information and have the user to calculate to get meaningful.

This is related to https://bugs.launchpad.net/nova/+bug/1300775 . I think it will be better if we can have the resource tracker to knows about the ratio.

--jyh

> 
> Best,
> -jay
> 
> 
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